Earlier this year, Semiconductor Research Corporation (SRC, Research Triangle, N.C.) sponsored research demonstrating a CMOS detector operating in the terahertz range. Now, Texas Instrument's has demonstrated a companion terahertz-range emitter created in cooperation with the SRC-sponsored Texas Analog Center of Excellence at the University of Texas at Dallas. TI's terahertz-range emitter uses a phase-locked loop (PLL) to stabilize its frequency, a necessity for making millimeter wavelength systems in CMOS commercially feasible.

"This is the highest frequency ever demonstrated for a phase-locked loop," claimed Brian Ginsburg, a design engineer at TI's Kilby Labs. "Stabilizing these ultra-high frequencies is [the] key to the future commercial success of millimeter wavelength CMOS applications [and] PLLs are fundamental to all high-performance electronics."

TI’s demonstration used an on-chip antenna that emits 390-GHz frequencies, but the researchers believe that improvements will enable the CMOS emitter to reach 600 GHz or higher using TI's 45-nm process technology.

"The [Federal Communications Commission] defines the terahertz range to be from 300 GHz to 3 THz," said Eunyoung Seok, a design engineer at TI's Kilby Labs. "For the future, we want to use TI's 45-nanometer process to cover more of this wider frequency range, as well as to increase our output power."

The current demonstration chip operates at 390 GHz using a multiplying PLL architecture with two frequency dividers in the feedback loop. The power emanating from the on-chip antenna was 2.2 microWatts.

In some applications, the ultra-high-frequency output from the on-chip antenna can be propagated and reflected by lenses and other optical components since the terahertz-range wavelengths are between the far infrared and microwave frequencies used for communications.